One type of solid state imager includes a substrate of single crystalline semiconductor material having along one surface thereof a plurality of detector areas for detecting radiation and converting the radiation to charge carriers, and transfer means along the detector areas for receiving the charge carriers and transferring them to an output terminal. One such type of detector commonly used is a Schottky-barrier detector formed of a layer of a conductive material forming a Schottky-barrier junction with the substrate. One type of transfer means used is a CCD. Such an imager is shown and described in the articles of W. F. Kosonocky et al., entitled "Design and Performance of 64.times.128 Element PtSi Schottky-barrier Infrared Charge-Coupled Device (IRCCD) Focal Plane Array", published in SPIE, Volume 344, Infrared Sensor Technology (1982), pages 66-77 and W. F. Kosonocky et al., entitled "160.times.244 Element PtSi Schottky-Barrier IR-CCD Image Sensor", published in IEEE Transactions On Electron Devices, Vol. ED-32, No. 8, August 1985, pp. 1564-1573. A problem with this type of imager is that the transfer means, such as the CCD, takes up room on the surface of the substrate so as to reduce the fill-factor of the device.
As described in U.S. Pat. No. 3,864,722 to J. E. Carnes, entitled "Radiation Sensing Arrays", issued Feb. 4, 1975, a CCD imager has been developed which has the Schottky-injection detector along one surface of a substrate of semiconductor material and a CCD transfer means along the opposite surface of the substrate. Radiation detected by the Schottky-barrier detector surface is converted to charge carriers and some of the carriers are injected into the substrate. The substrate is depleted so that the charge carriers move across the substrate to the channels of the CCD. Voltages are then clocked to the gates of the CCD to move the charge carriers along the channels to the output of the device. Although this device has an improved fill-factor, since the detector is across the entire surface of the substrate, this deiice has other problems resulting from the CCD being the collector of the charge carriers as well as the transfer means. As one set of charge is being transferred along the channels of the CCD, other charges are being collected. Thus, if a charge is not transferred along the channels fast enough, it can be interferred with by the new charges being collected thus causing smear.